1. Field of the Invention
The present invention relates broadly to the field of solar energy utilization and, more particularly, to a method of vacuum-sealing the integral heat transfer passage system of a solar absorber panel which minimizes the amount of welding required yet accomplishes the advantages of a fluid-tight, corrosion resistant system.
2. Description of the Prior Art
The rapid depletion of conventional sources of energy has resulted in an ever-widening search for alternatives to conventional sources such as petroleum and natural gas to meet the increasing demand for energy by our society today. One such viable source which is presently commanding a great deal of attention and research, development and in the deployment of experimental units is that of solar energy. Solar flat plate collectors may be employed, inter alia, as sources of heat for homes and buildings and for maintaining an adequate supply of hot water in such installations.
In general, the prior art contains many examples of different ways to utilize solar energy absorbed by flat plate collectors of various types and configurations. Solar flat plate collectors normally consist of a solar absorber plate having a black body or selective absorption surface which is utilized to absorb energy from solar radiation combined with a heat transfer system which removes useful heat from the absorber plate and conducts it to a place where it is utilized or stored. Solar collector panels have been utilized to heat a variety of fluid media through heat transfer systems utilizing the solar absorber plate. The higher heat transfer coefficient of liquid media together with the higher heat capacity per unit volume exhibited by such materials as opposed to gaseous fluids results in the ability to obtain an efficient collection of the solar energy absorbed.
Of primary concern in the construction of solar collector panels is the construction of the solar absorber itself. The efficiency of the entire solar energy system depends a great deal on the efficiency of collection and transfer of heat which takes place at the solar absorber panel. Because a great deal of area is normally required to absorb sufficient solar energy to heat a building using solar flat plate collectors, the cost of each collector is of prime consideration in deploying a solar flat plate collector system. Thus a primary goal in improving the overall cost of utilizing solar energy in relation to other available sources of energy lies in a reduction of the cost of producing solar absorber panels. This includes a reduction in the cost of both materials and labor and in the production of solar absorber panels having long life and durability. While the use of such materials as mild steel which is readily available and easily fabricated, reduces material cost, it is also susceptible to oxidation corrosion. It is also desirable from a cost standpoint to reduce the amount of welding necessary to fabricate a solar absorber panel. Thus, if the internal heat transfer passages of a mild steel absorber plate can be coated with a suitable corrosion-resistant material and a great deal of the welding can be avoided in the construction of that panel, a valuable cost savings may be realized.